Bowtie Shaped Roof Bow

ABSTRACT

A roof bow for a vehicle is provided that has a “bow-tie” shape including a central portion flanked by two triangular portions. The triangular portions are joined to right and left roof brackets that are, in turn, joined to right and left roof rails. The bow-tie roof bow may be assembled from extruded tubular parts. The bow-tie roof bow may be assembled in a clamshell structure including an upper shell and a lower shell that are joined together by welding. The roof bow may be formed in one piece as a sheet metal stamping having side portions that are wider than the central portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 14/844,624filed Sep. 3, 2015, which is a division of U.S. application Ser. No.14/049,611 filed Oct. 9, 2013, now U.S. Pat. No. 9,156,500 issued Oct.13, 2015, the disclosures of which are hereby incorporated in theirentirety by reference herein.

TECHNICAL FIELD

This disclosure relates to the structure of a roof bow for a vehicleroof that minimizes intrusions into the passenger compartment in sideimpact collision tests ad roof crush tests.

BACKGROUND

Roof bows are attached to vehicle roof structures to strengthen the roofand support the roof rails. Current roof rail designs include a railthat extends transversely across the vehicle roof from one roof rail tothe other roof rail and have a substantially uniform width as measuredin the fore-and-aft direction. Such roof rails do not include lateralsupporting reinforcements between the windshield header rail, the railextending between the B-pillars, and the rail extending between theC-pillars.

Vehicles are subjected to Federal Motor Vehicle Safety Standards (FMVSS)tests in the United States. In FMVSS Side Pole Impact Tests a pole isimpacted by the test vehicle that may engage the vehicle in a locationwhere the roof rail is not supported by a transversely extending rail.The unsupported portion of the roof rail may allow unacceptableintrusions into the passenger compartment. Vehicles are also subjectedto FMVSS Roof Crush Tests that apply an impact load to the vehicle roofin the area of the roof rail.

Improving test results in the above FMVSS tests is normally addressed byincreasing the section size and the thickness of the parts of the roofrail. Increasing the section size and thickness of the roof rails addsweight to the vehicle and may reduce visibility below the roof rail. Itis a current objective to reduce vehicle weight to achieve greater fuelefficiency. Any increase in weight is considered to be a problem.

The use of a K-shaped roof bow has been proposed to improve testperformance that is joined to the roof rail by welds and rivets. AK-shaped roof bow joined by welds or rivets to the roof rail mayseparate in the test and limit the effectiveness of such a design intransferring loads from the roof rails to the K-shaped roof bow.

This disclosure is directed to addressing the above problems and otherproblems as summarized below.

SUMMARY

According to one aspect of this disclosure, a roof bow is provided for avehicle having a roof. The roof bow includes a central portion thatextends transversely across the roof. The roof bow also includes a firstside portion on a first lateral end of the central portion. A secondside portion is provided on a second lateral end of the central portion.The first and second side portions may be first and second triangularportions that each define a triangular opening.

According to other aspects of this disclosure, the roof bow may includea lower shell that includes a lower portion of the central portion, thefirst triangular portion and second triangular portion. The roof bowalso may include an upper shell that includes an upper portion of thecentral portion, the first triangular portion and second triangularportion. The lower shell and the upper shell are joined together in aclam shell assembly. The upper and lower shells are sheet metalstampings that are formed of aluminum. The upper and lower shells arewelded together about their perimeter.

According to an alternative embodiment of this disclosure, the roof bowmay include a front extrusion that includes a front portion of thecentral portion and a front leg of the first triangular portion and afront leg of the second triangular portion. A rear extrusion may includea rear portion of the central portion and a rear leg of the firsttriangular portion and a rear leg of the second triangular portion. Aright side leg extrusion may is joined to the front leg of the firsttriangular portion and the rear leg of the first triangular portion. Aleft side leg extrusion is joined to the front leg of the secondtriangular portion and the rear leg of the second triangular portion.The front legs of the front extrusion and the rear legs of the rearextrusion may be joined to the right and left side extrusions by a miterjoint. The right and left side leg extrusions may each define aplurality of access openings for joining the roof bow to the vehicle.

According to further aspects of this disclosure, the triangular portionseach include a front leg that extends outwardly in a forward direction,a rear leg that extends outwardly in a rearward direction and a side legthat is joined to the front leg and rear leg and extends in alongitudinal vehicle direction. The side legs may each define aplurality of access openings for joining the roof bow to the vehicle.

The roof bow may include a front step flange and a rear step flange thatboth extend across the first side portion, the central portion, and thesecond side portion. The roof bow may also include a forward rib and arearward rib that extend laterally across the roof bow and divergeoutwardly in the first and second side portions.

According to another aspect of this disclosure as it relates to asupport structure for a vehicle roof panel, an outer roof panel isdisclosed that is supported by a right roof rail on a right side of theouter roof panel and a left roof rail on a left side of the outer roofpanel. A roof bow includes a central portion extending transverselyacross the roof with a first triangular portion on a first lateral endof the central portion that defines a first triangular opening. A secondtriangular portion on a second lateral end of the central portiondefines a second triangular opening. A right side bracket may beattached to the right side roof rail and the first triangular portion. Aleft side bracket may be attached to the left side roof rail and thesecond triangular portion.

According to other aspects of the disclosed roof, a right B-pillar and aleft B-pillar are provided and the right side bracket and the left sidebracket each extend both in front of and in back of the B-pillars to agreater extent that the first and second triangular portions of the roofbow. The right B-pillar and the left B-pillar may be laterally alignedwith the central portion.

According to an additional aspect of this disclosure a vehicle bodystructure is provided that includes an outer roof panel and a roof railsupporting a side of the roof panel. A B-pillar supports an intermediateportion of the roof rail and a bracket is attached to the roof rail thatextends fore-and-aft of the B-pillar. A roof bow has a central portionthat extends transversely across the roof panel. A front leg extendsoutwardly from the central portion in a forward direction to alongitudinally extending side leg. A rear leg extends outwardly from thecentral portion in a rearward direction to the side leg. An impact forcefrom a side impact collision test or a roof crush test with the vehicleis transferred to the bracket. The bracket transfers the impact force tothe side leg. The side leg, in turn, transfers the impact force to oneor both of the front leg and the rear leg. The front leg and rear legthen transfer the impact force to the central portion of the roof bow.

According to other aspects of the vehicle body structure, a lower shellmay be provided that includes a lower portion of the central portion,the front leg, the rear leg and the side leg. An upper shell may beprovided that includes an upper portion of the central portion, thefront leg, the rear leg and the side leg. The lower shell and the uppershell may be joined together in a clam shell assembly. The sheet metalstampings may be aluminum, and the lower shell and the upper shell maybe joined about a perimeter of each by welding.

According to an alternative body structure, a front extrusion mayinclude a front portion of the central portion and the front legs. Arear extrusion may include a rear portion of the central portion and therear legs. A side extrusion may be attached to a distal end of each ofthe front legs and a distal end of each of the rear legs with the sideextrusion being attached to the bracket.

The above aspects of this disclosure and other aspects are describedbelow in greater detail and with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top perspective view of the result of an impact on theprior art roof design after a FMVSS Side Pole Impact Test;

FIG. 1B is a diagrammatic view showing the load path for a prior artroof structure in a FMVSS Side Pole Impact Test;

FIG. 2 is a fragmentary perspective view of a “bow-tie” shaped roof bowassembled from extruded tubular component parts;

FIG. 3A is a perspective view of the “bow-tie” shaped roof bow shown inFIG. 2;

FIG. 3B is a fragmentary perspective view of a roof structure includingthe bow-tie roof bow shown in FIG. 2 attached to brackets and roof railson opposite sides of a vehicle;

FIG. 4 is a perspective view of a bow-tie roof bow made with a clamshellconstruction;

FIG. 5 is an exploded perspective view of the bow-tie roof bow of FIG. 4made having a clamshell construction with the two parts of the clamshellseparated from each other;

FIG. 6 is a fragmentary perspective view of a roof structure including abow-tie roof bow of FIG. 4 made with a clamshell construction attachedto right and left brackets and right and left roof rails in the area ofthe B-pillar;

FIG. 7 is a perspective view of a “bow-tie” shaped roof bow formed as aone-piece sheet metal stamping;

FIG. 8 is a cross-sectional view taken along the line 8-8 in FIG. 7;

FIG. 9 is a chart of a test of roof rail intrusion comparing anall-aluminum roof bow to a bow-tie roof bow design in a 20 mph FMVSSSide Pole Impact Test; and

FIG. 10 is a chart of a 5 mph FMVSS roof crush test comparing a baselineall-aluminum bow to the bow-tie shaped roof bow design.

DETAILED DESCRIPTION

The illustrated embodiments are disclosed with reference to thedrawings. However, it is to be understood that the disclosed embodimentsare intended to be merely examples that may be embodied in various andalternative forms. The figures are not necessarily to scale and somefeatures may be exaggerated or minimized to show details of particularcomponents. The specific structural and functional details disclosed arenot to be interpreted as limiting, but as a representative basis forteaching one skilled in the art how to practice the disclosed concepts.

Referring to FIG. 1A, a vehicle 10 made according to the teachings ofthe prior art is shown following a FMVSS side pole impact test. Thevehicle 10 includes a roof rail 12 that extends along the side of thevehicle 10. A-pillar 14 supports a windshield header 16. B-pillar 18 isaligned with a central bow 20. The roof rail 12 extends from theA-pillar 14 to the B-pillar 18. A circle 22 indicates the intrusion areawith the vehicle 10 contact at a pole 26, as shown in FIG. 1B.

Referring to FIG. 1B, the pole 26 is shown engaging the prior art roofrail 12 between the A-pillar 14 and the B-pillar 18. The impact forcedepicted in arrows showing that part of the force follows the directionof arrow A1 that, in turn, transfers the force to the windshield header16, as indicated by the arrow A2. Another portion of the force depictedby arrow A3 showing force being transferred through the roof rail 12 tothe central bow 20, as indicated by arrow A4.

Referring to FIGS. 2, 3A and 3B, a right roof rail 30 and a left roofrail 32 are connected by a bow-tie roof bow 36. The bow-tie roof bow 36in this embodiment is assembled from extruded parts to provide a strong,lightweight roof bow. The bow-tie roof bow 36 includes a central portion38 that extends between a right triangular portion 40 and a lefttriangular portion 42. A right bracket 44 and a left bracket 46 areattached to the right roof rail 30 and left roof rail 32, respectively.The right triangular portion 40 and left triangular portion 42 areconnected to the right bracket 44 and left bracket 46, respectively.

A front extrusion 48 and rear extrusion 50 are assembled together toform the central portion 38 and the right and left triangular portions40 and 42. A rear extrusion 50 is assembled to the front extrusion 48.The front extrusion 48 includes a front leg 52 that extends from thecentral portion to form the front of the triangular portions 40 and 42.A rear leg 54 is part of the rear extrusion 50 and forms a rear portionof the right and left triangular portions 40 and 42. A right sideextrusion 56 joins the front leg 52 and rear leg 54 on the right side ofthe roof bow 36. A left side extrusion 58 interconnects the front leg 52and rear leg 54 on the left side of the bow-tie roof bow 36. The frontand rear legs 52 and 54 are joined to the right side extrusion and leftside extrusion with a miter joint 60.

Access holes 62 are provided on the right side extrusion 56 and leftside extrusion 58 for assembling fasteners or welding the bow-tie roofbow 36 to the right bracket 44 and left bracket 46.

Referring to FIGS. 4 through 6, an alternative embodiment of a bow-tieroof bow 64 is illustrated that has a clamshell structure. The bow-tieroof bow 64 includes a central portion 68 that is flanked by a righttriangular portion 70 and a left triangular portion 72. The righttriangular portion 70 is attached to a right bracket 74. The lefttriangular portion 72 is connected to a left bracket 76. The bow-tieroof bow 64 includes an upper shell 78 and a lower shell 80 that areassembled together and welded about their periphery to form the bow-tieroof bow 64. The triangular portions 70, 72 each include a front leg 82and a rear leg 84 that extend forward and rearward, respectively, fromthe central portion 68. The right triangular portion 70 also includes aright side 86 and the left triangular portion 72 includes a left side88.

Access holes 90 are provided in the right side 86 and the left side 88to provide access for fasteners or welding.

In both the bow-tie roof bow 36 and bow-tie roof bow 64, the roof bowsare attached to the right brackets 44, 74 and left brackets 46, 76. Theright and left brackets have a greater longitudinal extent than theright and left sides 86 and 88 and the right side extrusion 56 and leftside extrusion 58. The triangular portions of the bow-tie roof bows 36and 64 extend to a greater extent longitudinally than the length of theconnection between the B-pillars 18 and roof rail 12. In the FMVSS SidePole Impact Test, the impact forces are transferred initially to theroof rail 12 then to one of the side brackets 76, 78. The forces arethen transferred to the sides 56, 58, 86, 88. The impact forces are thentransmitted to the central portions 38, 68 through the front legs 52, 82and rear legs 54, 84.

Referring to FIGS. 7 and 8, an alternative embodiment of a “bow-tie”shaped roof bow 100 is illustrated that may be formed in a sheet metalstamping operation. The stamped roof bow 100 includes a central portion102, a right side portion 104, and a left side portion 106. The rightside portion 104 is attached to a right bracket 108. The left sideportion 106 is attached to a left bracket (not shown) that is a mirrorimage of the right bracket 108. The right bracket 108 is attached to aroof rail 110 of the vehicle. The side portions 104 and 106 are widerthan the central portion 102 and are at least twice as wide as thecentral portion 102.

A front step flange 112 is formed at a front edge 114 of the roof bow100. A rear step flange 116 is formed at a rear edge 118 of the roof bow100. A forward rib 120 extends laterally across the roof bow 100 and arearward rib 122 extends laterally across the roof bow 100. The forwardrib 120 and rearward rib 122 diverge in the side portions 104 and 106and are parallel to each other in the central portion 102. The stepflanges 112 and 116 and the ribs 120 and 122 function to reinforce theroof bow 100.

Referring to FIG. 9, the bow-tie roof bows are shown compared to abaseline all aluminum roof bow. In the chart of FIG. 7, the baselineall-aluminum roof bows represented by the line A and the bow-tie roofbow is represented by line B. Comparing line B to line A, the intrusionis reduced by approximately 10 mm beginning at approximately 60milliseconds into the test through 90 milliseconds into the test.Reducing intrusion by 10 mm represents a substantial improvement in roofbow performance in the 20 mph FMVSS Side Pole Impact Test.

Referring to FIG. 10, another chart is provided of a 5 mph Roof CrushTest. Again, the baseline all-aluminum roof bow is represented by line Aand the bow-tie roof bow design is represented by line B. This testresult shows that the bow-tie roof bow design increases the force inMPAs of approximately 20 MPAs when averaged over the period of the testfrom approximately 30 mm to 80 mm. This represents an improvement ofapproximately 20% compared to the baseline all aluminum roof bow design.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the disclosed apparatusand method. Rather, the words used in the specification are words ofdescription rather than limitation, and it is understood that variouschanges may be made without departing from the spirit and scope of thedisclosure as claimed. The features of various implementing embodimentsmay be combined to form further embodiments of the disclosed concepts.

1. A roof bow for a vehicle having a roof comprising: a central portionhaving a first width extending transversely across the roof; a firstside portion on a first lateral end of the central portion; and a secondside portion on a second lateral end of the central portion, wherein thefirst and second lateral ends have a second width that is more thantwice as wide as the first width. 2-9. (canceled)
 10. The roof bow ofclaim 1 further comprising: a front step flange that extends across afront edge of the first side portion, the central portion, and thesecond side portion; and a rear step flange that extends across a rearedge of the first side portion, the central portion and the second sideportion.
 11. The roof bow of claim 10 further comprising: a forward ribextending laterally across the roof bow; and a rearward rib extendinglaterally across the roof bow, wherein the forward rib and the rearwardrib diverge outwardly in the first and second side portions, and whereinthe forward rib and rearward rib are parallel in the central portion.12. A support structure for a vehicle roof panel comprising: a rightroof rail supporting a right side of the roof panel; a left roof railsupporting a left side of the roof panel; a roof bow including a centralportion extending transversely across the roof panel, a first sideportion on a first lateral end of the central portion, and a second sideportion on a second lateral end of the central portion; a right sidebracket attached to the right roof rail and the first side portion; anda left side bracket attached to the left roof rail and the second sideportion.
 13. The support structure of claim 12 further comprising aright B-pillar and a left B-pillar, and wherein the right side bracketand the left side bracket each extend both in front of and in back ofthe B-pillars to a greater extent that the first and second sideportions of the roof bow.
 14. The support structure of claim 13 whereinthe right B-pillar and the left B-pillar are laterally aligned with thecentral portion.
 15. A vehicle body structure for supporting a roofpanel comprising: a roof rail supporting a side of the roof panel; aB-pillar supporting an intermediate portion of the roof rail; a bracketattached to the roof rail that extends fore-and-aft of the B-pillar; anda roof bow having a central portion that extends transversely across theroof panel, wherein the roof bow has first and second side portions thatextend outwardly from the central portion in a forward direction and arearward direction, wherein an impact force from a side impact collisionis transferred to the bracket, that transfers the impact force to one ofthe side portions, and that transfers the impact force to the centralportion of the roof bow. 16-20. (canceled)